Internally fired safety pilot gas burner



March 18, 1952 J. l.. HARRIS ETAL INTERNALLY FIRED SAFETY PILOT GAs BURNER Filed Nov. 12, 194e 4 0.1 E .v )n lllllll Il 8/ 5 m N inf/1% 7 www@ m 11 k 9? @Q E ,NLM n, 5 w 9 z n fw l H N L A JU l 3 2 ku f 6 m b/Miwfwwifhllln z 1. .Err M A f L u f l F V Patented Mar. 18, 1952 UNITED .sirenes raar-e l FFICE INTERNALLY FLRED SAFETY PILOT GAS BURNER Joh-n L. Harris, Whitefish Bay, `md Clifford Hotchkiss, Milwaukee, Wis., assignors to Perfex Corporation, Milwaukee, Wis., a corporation of Wisconsin YApplication N ovember 12, 1946, Serial No. 709,128

(Cl. 15S- 115) 7 Claims.

embodying relatively movable parts affording a speedy response suitable for controllably effecting a prompt shut-off of fuel feed `in the event the supply of fuel is terminated or the flow thereof becomes so slow as to render flame failure likely or probable, or operation of the burner undesirable.

Another object of the present invention is to provide a pilot burner structure embodying relatively movable, expandable parts constructed and combined in an improved manner aiiording a blow-out proof flame lsuitable for igniting a main burner and suitable for maintaining a workable temperature difference between such parts irrespective of variations in ambient .temperature.

Another object of the present invention is to provide an improved pilot burner structure embodying parts constructed and combined with each other and with a gas emitting nozzle .in a manner insuring the formation of a combustible mixture under conditions resulting in the production of a blow-.out proof flame having at all times a portion thereof disposed indirect hea-t imparting relation to one of .such parts, and another portion thereofcapable of igniting a burner disposed adjacent the pilot structure, irrespective of variations in fuel iiow over a .Wide range.

Still another object of the present invention is to provide a durable, relatively inexpensive and positively acting safety pilot ystructure vminimizing the number and intricacy of the parts thereof.

Another object of the present invention is to provide a safety pilot structure embodying passage forming parts constructed and combined with each other and with a gas emitting nozzle so as to provide a blow-out proof igniting flame partially conned within an inner passage Aat all times, and of such character that the flame moves farther into such passage and imparts more heat to the flame confining walls .thereof as the oW of fuel increases.

Another'object of the .present invention is to provide a pilot burner .Structure embodying a fuel emitting nozzle and parts constructed and combined vfor relative expansion in generally spacedpassage forming relation in a manner insuring the formation of a blow-out proof ignitingflame partially confined at all times within a passage afforded by one of such parts and in a manner insuring the transfer of heat from one to another of the parts primarily by conduction through joined portions thereof.

Another object of the present invention is to" provide a pilot burner structure embodying a fuel emitting nozzle and parts constructed and combined for relative expansion in generally spaced passage forming relation in a manner insuring the yformation of a blow-out proof igniting flame partially confined at all times within a passage aiforded by one of such parts and in a manner maintaining a marked workable difference in the temperature between said one part and another of the parts Ajunctioned therewith,

irrespective of variations in ambient temperature and irrespective of variations in fuel iiow throughout a normally expectant range.

The construction and application of apparatus embodying the invention will become readily apparent as the disclosure progresses and points-out additional objects, advantages and features of construction considered of special importance, and in some instances of general application, although shown and described as applied to a switch actuating mechanism. Accordingly, the present invention may be considered as comprising partsconstructed and/or combined or correlated as-hereinafter more fully set forth in the appended claims and in the detailed description, reference being had to the accompanying drawing illustrating but one embodimentl of the invention, and in which:

Fig. 1 is a perspective view of a safety pilot apparatus embodying theinvention;

Fig. 2 is an enlarged view similar to Fig. 1, with parts cut away to show the construction, combination, and coaction of parts;

Fig. 3 is a central, vertical section taken through the pilot valve structure and through the switch mechanism mounted thereon;

*Fig 4 is v`a-section taken on line 4-4 of Fig. 3;

Fig. 51's a central vertical section through the upper portion of thetube structure shown in Figs. 2 and 3 illustrating the manner in which the iiame movesaway from the nozzle when the gas pressure is low;

Fig. 6 isa section taken on line 6 5 of Fig. 5; and

l Fig. 7 is aview similar to Fig. 5 illustrating the aseasori path of air fiow, the formation of a combustible mixture, and the flame resulting therefrom.

ln the illustrated embodiment of the invention. I designates a generally cylindrical body member having a bore or passage 2 extending coaxially therethrough. Passage 2 is counter-bored to provide an internal shoulder 3 adjacent one end thereof, and is additionally counter-bored or further enlarged immediately adjacent shoulder 3 and adjacent the inlet end thereof. enlargement adjacent shoulder 3 is internally threaded, as is also the inlet end portion of the passage, the latter providingY means for connecting body member I to a suitable source of gas supply, such as a conduit (not shown). A nozzle member 4 projects or extends through passage 2 to a point considerably beyond body member I and is provided with an external shoulder 6 adapted for seating engagement with an element 'I having an external portion in screw threaded engagement with the internally threaded portion of passage 2 and having an opening 3 therethrough in coaxial alignment with the passage 9 in the nozzle'member 4. The discharge end of the nozzle Vmember 4 may be provided with a suitable cap I I which is formed with a metering orifice. The inlet end portion of body member I is provided with an external shoulder I2.

An outer tube I3 is disposed in telescoped relation about body member I with an end thereof abutting shoulder I2. Tube I3 may be fixedly secured to body member I in any suitable manner, preferably a press fit. -The end of tube I3 remote from body member I is provided with an annular outer olf-set flange I4 to which is secured, in any suitable manner, such as by screws or rivets I6 (only one of which is shown), a cap structure Il having a centrally disposed elongated opening I8 therethrough. Cap'structure l'I may also be provided with a flame deflecting member I9 which in turn may be secured to the cap structure by means of the screws or rivets I6, and includes an intermediate portion 2| disposed in transverse spaced opposed relation with respect to elongated opening I8.

Disposed within and spaced from outer tube I3 is an inner tube having a portion 22 of generally circular cross. section disposed in spaced surrounding relation with respect to nozzle'member 4 and which merges into a mixture forming and flame conning portion 23 of generally elliptical or elongated cross section, aligned with andconforming in general with the shape of the elongated opening I8 in the cap structure I'. The portion of the inner tube of elliptical or elongated cross section has opposed end-wall portions thereof adjacent its discharge end cut away or removed to provide a pair of aligned openings 24 therethrough placing the upper interior or discharge end thereof in communication with the passage 25 between the tubes. The inner tube has opposed wall portions 26 at the discharge end thereof bent over to abuttingly engage the underside of cap structure I'I and is preferably flxedly secured thereto as by means of spot welds 27. The lower end of cylindrical portion 22 of the inner tube is provided with an annular control member actuator 28 fixed thereto for movement therewith relative to nozzle member 4. Actuator 28 is disposed in passage closing relation with respect to space 29 between nozzle member 4 and inner tube portion 22 and is provided with an external annular groove 3|.

Secured to outer tube I3 is a bracket having The 1 w binding posts or terminals 44.

a central portion 32 disposed in abutting relation with respect to the external side wall of tube I3 and similar off-set edge portions 33 spaced from tube I3 and terminating in edge flanges 34 bent inward toward the tube for braced edge engagement therewith. Each flange 34 is provided with a pair of vertically spaced internally threaded holes 36. A hollow switch box 3l formed of suitable ceramic insulating material, such as lava, is disposed with its marginal edges abutting the bracket side edges 33 to form a switch enclosing housing therewith. Box 3l is preferably detachably secured to the bracket by means of screws 30 passing through openings therein and into aligned internally threaded openings in the bracket side portions 33. The lower or bottom wall 39 of box 3'I is preferably cut away to provide an opening for inserting wires therethrough. The wall of box 3l disposed in spaced opposed relation with respect to the bracket is provided with a pair of spaced plate-like elements 42 and 43 mounting similar screw type Plate-like elements 42 and 43 are secured to box 3l by means of rivets or the like 46. Plate element 42 is provided with an adjustable contact 4l. Box 31 also .mounts a spring blade 43 with its free portion and of outer tube I3 disposed directly opposite the actuator 28 carried by the inner tube are cut away to provide an opening 52 therethrough. rlhe opposed portion of spring blade 48 is provided with an actuating arm or knob 53 which extends through such opening and into the external groove 3| formed in actuator 28. The bracket and outer tube also have wall portions thereof cut away directly opposite the contact 4S on spring blade 48 to provide a relief opening 54 permitting a greater degree of contact opening movement of the spring blade than would otherwise be permitted.

Switch box 3l is preferably enclosed in a cover 56 spaced therefrom and secured to the bracket by means of screws 5'I passing through openings in the cover alignable with the internally threaded openings 36 in the bracket flange portions 34. The bottom wall of the cover 56 has a slot or opening 58 therethrough aligned with the opening 4 I in the bottom wall of'switch box 3l for receiving the wires or other conductors attached to terminals 44. Outer tube I3 is provided with an opening 56 therethrough placing the passage 24 between the inner and outer tubes in communica-I ing 59, and due to the inspirating effect of the fuel emitted from nozzle member 4 air enters the upper portion of the inner tube through opening 24 and flows downward therein adjacent the end walls thereof in counter-flow relation to the fuel flow, as indicated bythe :arrows von Fig. 7. Air, upon .entering the inner tube as just 'described, mixes with the gas flowing from nozzle member 4 immediately adjacent thereto, and oonsequently a combustible mixture is formed within the' portion of the inner tube of non-symmetrical or Velongated cross section ata point adjacent its junction with the portion of cylindrical cross-section. Upon'igniting the combustible mixture thus formed, the resulting fiame projects from the tube generally in the manner indicated Vin Fig. 7 And it has been found that the nozzle end of `the flame moves toward and away from, but not out of,

' the discharge end of the tube as the fuel `flow decreases and in-creases, respectively. Consequently, the flame is always partially confined within and directly heats the upper portion of thenner tube, thus maintaining a workable .temperatu're difference between lthe'inner and outer tubes, irrespective of variations'in fuel fiow and irrespective of variations in ambient temperature. This result is primarily attributable Ato the-construction combining the inner tube with the rnozzle member A in a manner such that though the tube may move relative to the nozzle, only an insignicant amount of air may enter between the tube and nozzle, the flow of fuel from the nozzle being therefore, capable of causing air to enter the tube through the openings 24 and to then fiow toward the nozzle in counter-flow relation to the fuel iiow.

Stated somewhat differently, heat is conducted from the hot spot portion of the inner tube, the portion directly contacted by the fiame, in both directions therethrough to the upper and lower portions of the outer tube joined therewith. And in this connection it should be noted that the temperature difference between the inner and outer tubes theoretically will remain nearly constant as the ambient temperature changes, since although an increase in ambient temperature tends to decrease the rate of heat dissipation from the outer tube, due to a corresponding increase in the temperature thereof, the temperature of the inner tube is also increased ran amount corresponding to the increase in ambient temperature due to the fact that though heat input to the inner tube remains substantially constant for a given fuel flow ythe higher temperature of the outer tube, because of the increased ambient temperature results in a decrease in the temperature gradient between the inner and outer tubes and therefore a decrease inthe rate of heat conduction from the inner tube to the outer tube, thereby increasing vthe temperature of the inner tube until the rate of heat conduction from the inner tube to the outer tube is again equal to the Lrate of heat input to the inner tube. Moreover, it should also be noted that the rate of heat input to the inner tube, and thereby the temperature difference between the inner and outer tubes, will vary as the iiow of fuel changes, since the size of the portion of the flame confined within the inner tube varies accordingly. However, the temperature of the inner tube will always be considerably higher than that of the outer tube, irrespective of variations in ambient temperature, so long as the iiow of fuel continues and is in excess of an abnormally low or undesirable'value. Under such abnormal conditions it should be apparent that the temperature of the inner and outer tubes will be nearly alike, since the flame moves upward in the inner tube to a point such that it impartsnearly Vas much heat tothe outer tube as it does tothe inner tube. In general, it will be vseen .that for all normal vranges of fuel flow, the `herein .described pilot burner structure maintains an veffective temperature .difference throughout the normal range of fuel fiow between the inner and outer tubes which varies in accordance with changes in fuel now.

In Figs. 2 and 3, the various parts are shown in positions conforming to a cold or shutdown condition .in which the out-er and inner .tubes are at substantially the same temperature, .and in which the contacts 41 and 49 are open. If :the owof fuel is Yresumed and the combustiblemixture ignited, the `temperature of the inner ,tube will almost immediately become considerably higher .than the temperature of the outer tube. due to .the direct heating effect of the confined portion of the flame. Consequently, the inner tube will expand relative to the outer tube fand cause the lower or nozzle end of the former to move longitudinally relative to the latter in a direction effecting a contact closing movementof actuator 28 and switch arm e8. As previously pointed out, a variation in fuel iiow ywill `vary the length of that portion of the flame confined within' the inner tube and consequently the temperature of the inner tube, and also thetemperature ofthe outer tube. However, variations in fuel iiow will not effect a switch opening movement of the switch actuator carried bythe free end of the inner tube unless the ow of fuel ceases, or the rate thereof decreases to an abnormally low or undesirable value. In this connection, best results are obtained with a construction affording a iiame confining passage having a cross-sectional configuration suchthat the fiame will directly contact one or more vwall portions of the passage-defining structure with atleast one wall portion thereof spaced from theflame sufficiently to afford an air inspirating duct or passage portion such that the flow of fuel Ifrom the nozzlecauses air to enter `the passage at a point remote from the nozzle end thereof, and to then flow toward the nozzle in counter-How relation to the fuel flow. For example, a flame conning passage having an elongated or .non-symmetrical cross-sectional configuration as herein illustrated affords .two such ducts or passage portions. However, a passage having a cross-sectional configuration affording only one such duct or passage portion will operate satisfactorily, and in fact better than a passage of circular cross-section, since with the latter form of passage it is likely that the confined flame will be entirely surrounded by a thin layer of in-flowing air, which tends to reduce the rate of heat transfer from the flame to the walls defining the passage. In general, the inner and outer tubes may be formed of any suitable material, although it is preferable to select materials having a high degree of corrosive resistance and being capable of withstanding high temperatures. And in order to compensate for a decrease in the temperature difference between the inner and outer tubes caused by the nozzle end of theiconfined portion of the fiame moving upward toward the discharge end of the inner tube and thereby increasing the effective range of operation, it may be desirable to select tubematerials having different coefcients of expansion, there being stainless steel alloys on the market vparticularly'suitable for such application.

Apparatus embodying the invention may be y,of a form differing materially from that herein shown and described .forpurposes of illustration.

And it should therefore be understood that it is notintended to limit the invention to apparatus and parts constructed and/or combined in the exact manner herein disclosed, as various modications within the scope of the appended claims may occur to persons skilled in the art.

What is claimed is:

1. A safety pilot burnercomprising a fuel emitting nozzle, a first tube forming a mixing and flame confining passage extending from said nozzle in the general direction of fuel iiow to a discharge end opening to atmosphere, the portion of said first tube adjacent said discharge end having a cross-section other than circular, a second tube disposed in surrounding, spaced relation with said first tube and having one end adjacent said discharge end of said firsttube, a heat conducting member rigidly uniting said one end of said second tube and said discharge end of said first tube and forming an end-wall closing the space between said tubes, a support fixedly mounting the other end of said second tube, said first tube having a relatively high thermal coefficient of expansion and said second tube having a relatively lower thermal coefiicient of expansion, control means operatively connected to said first tube and actuated by expansion of said first tube, an opening in said second tube adjacent said other end thereof for admitting air to the space between'said first and second tubes, the wall of the other than circular cross-sectioned. portion of said first tube having an opening therein at a point furthest from the central longitudinal axis of said first tube, whereby flow of fuel through said first tube causesair to flow from said space between said first and second tubes, through said opening in said first tube and to then fiow through said first tube toward said nozzle in counterfiow relation to the fuel flow with a minimum cooling effect on said first tube and a maximum cooling effect on said second tube.

2. A safety pilot burner comprising a fuel emitting nozzle, a first thermally expansible tube forming a mixing and flame confining passage extending from said nozzle in the general direction of fuel flow to a discharge end opening to atmosphere, the portion of said first tube adjacent said discharge end having a cross-section other than circular, a second thermally expansible tube disposed in surrounding, spaced relation with said first tube and having one end adjacent said discharge end of said first tube, a heat conducting member rigidly uniting Said one end of said second tube and said discharge end of said first tube and forming an end-wall closing the space between said tubes, a support .fixedly mounting said other end of said second tube, control means operatively connected to said first tube and actuated by expansion of said first tube, an opening in said second tube adjacent said other end thereof for admitting air to the space between said first and second tubes, the Wall of the other than circular cross-sectioned portion of said first tube having an opening therein at a point furthest from the central longitudinal axis of said first tube, whereby flow of fuel through said first tube causes air to flow from said space between said first and second tubes, through said opening in said rst tube and to then flow through said first tube toward said nozzle in counter-flow relation to the fuel flow 'with a minimum cooling effect on said first tube permitting maximum thermal expansion thereof and a maximum cooling effect on said second tube permitting minimum thermal expansion thereof.

3. A safety pilot burner comprising a fuel emitting nozzle, a first thermally expansible tube forming a mixing and fiame confining passage extending from said nozzle in the general direction of fuel fiow to a discharge end opening to atmosphere, the pontion of said first tube adjacent said discharge end having a cross-section other than circular, a second thermally expansible tube disposed in surrounding, spaced relation with said first tube and having one end adjacent said discharge end of said first tube, means rigidly uniting said one end of said second tube and said discharge end of said first tube and forming an end-wall closing the space between said tubes, said last mentioned means including a heat conducting member forming a path of relatively high heat conductance between said tubes, a support flxedly mounting the other end of said second tube, control means operatively connected to said first tube and actuated by expansion of said first tube, an opening in said second tube adjacent said other end thereof for admitting air to the space between said first and second tubes, the wall of the other than circular cross-sectioned portion of said first tube having an opening therein at a point furthest from the central longitudinal axis of said first tube, whereby fiow of fuel through said first tube causes air to flow from said space between said first and second tubes, through said opening in said first tube and to then fiow through said first tube toward said nozzle in counter-flow relation to the fuel flow with a minimum cooling eect on said first tube permitting maximum thermal expansion thereof and a maximum cooling effect on said second tube permitting minimum thermal expansion thereof.

4. A safety pilot burner comprising a fuel emitting nozzle, a first thermally expansible tube forming a mixing and fiame confining passage extending from said nozzle in the general direction of fuel flow to a discharge end opening to. atmosphere, the portion of said first tube adjacent said discharge end having a generally elliptical cross-section, a second thermally expansible tube disposed in surrounding, spaced relation with said first tube and having one end adjacenty said discharge end of said first tube, means rigidly Y uniting said one end of said second tube and said discharge end of said first tube and forming an end-wall closing the space between said tubes, said last mentioned means including a heat conducting member forming a path of relatively high heat conductance between said first and second tubes, a support fixedly mounting the other end of said second tube, control means operatively connected to said first tube and actuated by expansion of said first tube, an opening in said second tube adjacent said other end thereof for admitting air to the Aspace between said first and second tubes, the wall of the elliptical crosssectioned portion of said first tube having an opening therein disposed at one endpoint of the major axis of the elliptical cross-section, whereby flow of fuel through said first tube causes air to ow from said'space between said first and second tubes, through said opening in said rst tube and to then fiow through said first tube toward said nozzle in counter-now relation to the fuel flow with a minimum cooling effect'on said first tube permitting maximum thermal expansion thereof and a maximum cooling effect on said second tube permitting minimum thermal expansion thereof. 1

5. A safety pilot burner comprising a fuel emitting nozzle, a first tube forming a mixing and flame confining passage extending from said nozzle in the general direction of fuel flow to a discharge end opening to atmosphere the portion of said first tube adjacent said discharge end having a cross-section other than circular, a second tube disposed in surrounding, spaced relation with said first tube and having one end adjacent said discharge end of said rst tube, means rigidly uniting said one end of said second tube and said discharge end of said first tube and forming an end wall closing the space between said tubes, said last mentioned means including a heat conducting member forming a path of relatively high heat conductance between said tubes, a support iixedly mounting the other end of said second tube, said first tube having a relatively high thermal coefficient of expansion and said second tube having a relatively lower thermal coefficient of expansion, control means operatively connected to said first tube and actuated by expansion of said first tube, an opening in said second tube Aadjacent said other end thereof for admitting air to the space between said tubes, the wall of the other than circular cross-sectioned portion of said first tube having an opening therein Vat a point furthest from the central longitudinal axis of said first tube, whereby fiow of fuel through said first tube causes air to fiow from said space between said rst and second tubes, through said opening in said first tube and to then fiow through said first tube toward said nozzle in counter-now relation to the fuel iiow with a minimum cooling effect on said first tube and a maximum cooling effect on said second tube.

6. A safety pilot burner comprising a fuel emitting nozzle, a first thermally expansible tube forming a mixing and fiame confining passage extending from said nozzle in the general direction of fuel flow to a discharge end opening to atmosphere, the portion of said first tube adjacent said discharge end having a generally elliptical cross-section, a second thermally expansible tube disposed in surrounding, spaced relation with said first tube and having one end adjacent said discharge end of said first tube, means rigidly uniting said one end of' said second tube and said discharge end of said first tube and forming an end-wall closing the space between said tubes, said last mentioned means including a heat conducting member forming a path of relatively high heat conductance between said tubes, a support fixedly mounting the other end of said second tube, control means operatively connected to said first tube and actuated by expansion of said first tube, an opening in said second tube adjacent said other end thereof for admitting air to the space between said first and second tubes, the wall of the elliptical cross-sectioned portion of said first tube having openings therein disposed at Vthe endpoints of the major axis of the elliptical crosssection,v whereby fiow of fuel through said rst tube causes air to fiow Afrom said space between said first and second tubes, through said opening in said'first tube and to then flow through said tube.

Vfirst tube toward said nozzle in counter-flow relation to the fuel-iiow with a minimum cooling effect on said first tube permitting maximum thermal expansion thereof and a maximum cooling effect on said second tube permitting minimum thermal expansion thereof.

- 7. A safety pilot burner comprising a fuel emitting nozzle, a first tube forming a mixing and iame confining passage extending from said nozzle inv the general direction of fuel fiow to a discharge end opening to atmosphere, the portion of said first tube adjacent said discharge end having a generally elliptical cross-section, a second tube disposed in surrounding, spaced relation with said first tube and having one end adjacent sfaid discharge end of said first tube, means rigidly uniting said one end of said second tube and nlsaid discharge end of said rst tube and forming an end-wall closing the space between said tubes, said last mentioned means including a heat conducting member forming a path of relatively vhigh heat conductance between said tubes. a support fixedly mounting the other end of said second tube, said first tube having a relatively high thermal coefficient of expansion and said second tube having a relatively lower thermal coefficient of expansion, control means operatively connected to said first tube and actuated by expansion of said first tube, an opening in said second tube adjacent said other end thereof for admitting air to the space between said first and second tubes, the wall of the elliptical cross-sectioned portion of said first tube having openings therein disposed at the endpoints of the major axis of the `elliptical cross-section, whereby iiow of fuel through said first tube causes air to ow from said space between said first and second tubes,

v*through said opening in said rst tube and to then new through said first tube toward said nozzle in counter-now relation to the fuel-flow with a minimum cooling effect on said first tube and a maximum cooling effect on said second JOHN L. HARRIS. CLIFFORD HOTCHKISS.

REFERENCES CITED The following references.are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 434,013 Barker Aug. 12, 1890 1,271,498 Blanchard July 2, 1918 1,353,217 Chappelle Sept. 21, 1920 1,434,256 Thompson Oct. 31, 1922 1,692,382 Nuss Nov. 20, 1928 1,933,318 Doen Oct. 31, 1933 1,963 957 Cunningham June 26, 1934 2,100,681 Arquint Nov. 30, 1937 2,367,119 Hess Jan. 9, 1945 2,427,545 Berger Sept. 16, 1947 'FOREIGN PATENTS iiumber Country Date 376,739 Great Britain June 30, 1932 

